Cannibalism in the tiger prawn Penaeus Monodon fabricius in nursery rearing phase

Abstract

Factors influencing the rate of cannibalism in the post-larvae and Juveniles of Penaeus monodon, were investigated under laboratory conditions. Cannibalism was found to be positively density dependent, significantly suppressed by shelter and negatively correlated to food availability and feeding frequency. With the increase in population density there was an increase in the rate of cannibalism. Provision of different additional sub¬strates in the rearing tanks was found to help in reducing cannibalism. Of the various substrates tested, clam shells and black polythene raffia were found to be the best shelters suitable for reducing cannibalism and assuring high carrying capacity. Feeding frequency was found to have greatest influence on cannibalism, which decreased with increase in feeding frequency. In P. monodon post-larvae cannibalism is invariably associated with attack made on animals undergoing moulting and is independent on the size of the victim. A high rate of cannibalism was observed during the early post-larval phase and it progressively decreased towards the late post-larval stage and juvenile stage, may be due to the decreased moulting frequency and acclimation to new rearing conditions and artificial feed. Substantial variation in size and growth rate was observed among, individuals at all stocking densities. The marked difference in individual growth rate observed within the group could be due to the interaction of various intrinsic and extrinsic factors.